TweetFollow Us on Twitter

June 94 - Somewhere in QuickTime

SOMEWHERE IN QUICKTIME

Basic Movie Playback Support

PETER HODDIE


Adding basic QuickTime movie playback support to most applications is simple, often just one day's work. Developers who want to do this turn first to Inside Macintosh: QuickTime , where it says to use a movie controller component. In Inside Macintosh: QuickTime Components,  you find some elementary movie controller code samples, followed by a large reference section. This is usually enough to get started, but there are a few common problems. This column addresses some of them, with special attention to compatibility with future QuickTime releases. It assumes you're familiar with basic QuickTime and movie controller concepts.

OPENMOVIEFILE
All QuickTime movie files contain a movie resource, usually stored in the file's resource fork, and the actual movie data, stored in the file's data fork. To support cross-platform QuickTime movies, QuickTime's Movie Toolbox also allows the movie resource to be stored in the data fork along with the movie's data. (To learn how this is done, see John Wang's Somewhere in QuickTime column in develop  Issue 17.) The usual sequence of calls to load a QuickTime movie from a file is: OpenMovieFile, NewMovieFromFile, CloseMovieFile.

In the common case of the movie resource stored in the resource fork, OpenMovieFile returns a file reference to the resource fork of the movie file, NewMovieFromFile loads the movie resource from that resource fork and creates a QuickTime movie, and CloseMovieFile closes the resource fork.

But if the movie was created on a computer running Microsoft Windows and QuickTime for Windows (using AdobeTM Premiere, for example), the file won't have a resource fork. Still, you can use the exact same sequence of calls. When OpenMovieFile is called, the file reference returned refers to the data fork; NewMovieFromFile loads the movie from the data fork, and CloseMovieFile closes the data fork.

Some developers don't use OpenMovieFile; they use FSpOpenResFile instead. While this works fine with movies made specifically for the Macintosh, it fails miserably otherwise. There's a sample movie with no resource fork, QuickBuck, on this issue's CD, so you can test this situation with your applications.

If you need to know whether OpenMovieFile opened the resource fork or the data fork, you can examine the file reference it returns, as follows:

pascal Boolean IsDataFork(short fileReference)
{
    FCBPBRec    anFCB;
    Str63       fName;

    anFCB.ioVRefNum = 0;
    anFCB.ioRefNum = fileReference;
    anFCB.ioFCBIndx = 0;
    fName[0] = 0;
    anFCB.ioNamePtr = (StringPtr)fName;

    if (PBGetFCBInfoSync(&anFCB) != noErr)
        return false;

    return (anFCB.ioFCBFlags & 0x0200) == 0;
}

NEWMOVIECONTROLLER
When you need a user interface for playing a movie, you should use NewMovieController to create a movie controller appropriate for use with that movie.

A common mistake is to instead use the Component Manager routine FindNextComponent or OpenDefaultComponent to locate a movie controller. This finds the first movie controller in the system's list of registered components. QuickTime has always contained only one movie controller, so this worked fine. However, future versions of QuickTime will almost certainly include other movie controllers, so the first one isn't necessarily the most appropriate one.

To help track down those offending applications that don't use NewMovieController, there's a system extension on this issue's CD which contains a different movie controller. You'll also find a movie, Other Controller Movie, that should  invoke the sample movie controller. If any other movie invokes the sample movie controller, or if Other Controller Movie invokes the standard movie controller, the application you're testing isn't using NewMovieController. This will cause undesirable results in the not-so-distant future.

UPDATE EVENTS
If you use a movie controller in the recommended way (that is, you allow all events to be filtered through MCIsPlayerEvent), it updates all areas of the window covered by the movie and the movie's controls. Usually that's all a window contains, so all update events are completely handled by the movie controller. This works so well that some developers actually forget to support update events at all.

Unfortunately, it's not always so simple. QuickTime movies aren't always rectangular. If the movie is round and the window is rectangular (as in Figure 1), there are areas in the window that are not covered by the movie or the movie controls. Any update events in these areas are the responsibility of the application. [IMAGE 022-025_Somewhere_in_QT_2.GIF]

Figure 1. A nonrectangular movie

For applications using MCIsPlayerEvent, handling update events is easy:

BeginUpdate(theWindow);
EraseRect(&theWindow->portRect);
EndUpdate(theWindow);

This sample code erases all areas of the window besides the movie and its controls. Normally, erasing the portRect of the window would erase the entire window, but MCIsPlayerEvent sets the update region to just the areas it didn't already handle.

If you don't handle update events, things are even worse than you might think. The window won't be updated correctly, but more important, the operating system will keep generating new update events. Update events have a higher priority than idle events, so the system will never generate idle events -- the movie will receive no time to play.

A sample round movie is provided on this issue's CD so that you can test your handling of update events.

KEYSTROKES
The standard movie controller provides for extensive keyboard control from the user but ignores keystrokes by default. They can be enabled with a single line of code:

MCDoAction(mc, mcActionSetKeysEnabled, (void *)true);

You might want to enable keystrokes only under certain circumstances. For example, a word processor might allow the movie controller to receive keystrokes only when a movie is selected. You can use the mcActionSetKeysEnabled action to enable and disable keystrokes as necessary.

MOUSE CLICKS
All applications that use the standard movie controller pass mouse clicks on to the controller. But not all applications pass mouse clicks made on the movie itself. Failure to pass such clicks will cause problems with any future movie controllers that allow the user to interact directly with the contents of the movie. For example, a movie controller might allow the user to pan around the image by dragging on the movie; if mouse clicks aren't passed through, using either MCClick or MCIsPlayerEvent, this feature won't work.

MOVIE CONTROLLER HELP
The standard Apple movie controller is simple enough for most people to understand immediately, but it supports help balloons anyway (future movie controllers might be less obvious). If Balloon Help is turned on, the standard movie controller automatically displays help for its various controls, as well as for the QuickTime movie itself. You don't have to do anything at all for this to work.

A problem can arise if your application puts up its own help balloons. Since QuickTime movies are often embedded in a larger document, the help balloons may conflict. The result is that the movie controller's help balloon alternates with the application's help balloon. (Use Balloon Help with the Scrapbook desk accessory included with QuickTime to see what this looks like.)

The preferred solution is to stop the application from displaying a help balloon when the cursor is over a QuickTime movie or movie control. It's easy to tell whether a given point in a window intersects the movie:

Boolean PointInMovieController(MovieController
        mc, WindowPtr w, Point where)
{
    RgnHandle   rgn;
    Boolean     result = false;

    rgn = MCGetWindowRgn(mc, w);
    if (rgn != nil) {
        result = PtInRgn(where, rgn);
        DisposeRgn(rgn);
    }
    return result;
}

A second solution is to stop the movie controller from displaying its help balloons -- necessary if you want to display your own help for QuickTime movies. To do this, install an action filter on the movie controller. Every action that occurs in the movie controller (play, step, update, key down, and so on) is passed through a single filter function. Through this filter, an application can gain access to all activity that occurs in the movie controller.

The MegaMovies application on this issue's CD provides a window that displays events that pass through the action filter. The action of interest is mcActionShowBalloon. When this action is sent, QuickTime is about to put up a new help balloon. One of the parameters passed to the action filter is a pointer to a Boolean. The filter can set this Boolean to false to tell the movie controller not to show a balloon. The following code fragments show how to install a simple action filter to prevent the movie controller from displaying help balloons.

pascal Boolean noBalloonsActionFilter 
                (MovieController mc, short action, 
                 void *params, long refCon)
{
    if (action == mcActionShowBalloon)
        *(Boolean *)params = false;
    return false;
}

. . .
MCSetActionFilterWithRefCon(mc, 
        &noBalloonsActionFilter, 0);

CURSOR SHAPE
Many applications change the shape of the cursor depending on what it's currently over. The standard movie controller never changes the cursor, but other movie controllers might want to. Unfortunately, many applications need to control the cursor themselves -- when a movie controller changes the cursor, these applications change it back immediately.

A simple solution is for applications to change the cursor only when it's first placed over a movie. (To determine whether a point is over the movie, use PointInMovieController.) After that, let the movie controller control the cursor until it exits the area over the movie. To give the movie controller the opportunity to change the cursor's shape, you must call either MCIsPlayerEvent or MCIdle frequently while the cursor is over the movie, even if the movie is stopped. The sample movie controller on this issue's CD changes the cursor when it's over the movie, providing an easy way to debug such a scheme.

WINDOW ALIGNMENT
A simple way to improve a QuickTime movie's playback performance is to ensure that the movie is at a good location on the screen. The exact definition of a "good location" varies, based on the screen depth and the processor. A typical good location is one where the first pixel of each scan line begins on a long-word boundary. This allows the decompressors to write data in the most efficientway. On slower machines, proper placement can provide the necessary performance improvement to deliver smooth playback.

Fortunately, applications don't have to understand the details of how to find a good location. QuickTime's Image Compression Manager provides routines to position a window at these locations. When you create a window, you can use AlignWindow to move it to a good location before making it visible. If a window is to be moved, AlignScreenRect will modify the chosen location to make it a good location. When the user drags a window, call DragAlignedWindow instead of DragWindow to place the window in a good location. Examples of these calls are shown below.

WindowPtr   w;
Movie       m;
Rect            r;

// Code to create a properly aligned window.
w = GetNewCWindow(128, nil, (WindowPtr)-1);
m = getMovie();
GetMovieBox(m, &r);
AlignWindow(w, false, &r, nil);

// Code to drag a window with a movie in it and
// keep the window aligned properly.
GetMovieBox(m, &r);
DragAlignedWindow(w, theEvent.where, nil, &r, nil);

These alignment routines were added in QuickTime 1.5, so make sure that QuickTime 1.5 or later is installed before you call them.

MOVIE CONTROLLER EDITING
The standard movie controller supports the editing commands Undo, Cut, Copy, Paste, and Clear, but this functionality is turned off by default. To turn it on, call MCEnableEditing as follows:

MCEnableEditing(mc, true);

You can then use movie controller routines to implement editing:

Movie       m = nil;

switch (editMenuSelection) {
    case menuUndo:      MCUndo(mc);
                            break;
    case menuCut:       m = MCCut(mc);
                            break;
    case menuCopy:      m = MCCopy(mc);
                            break;
    case menuPaste: MCPaste(mc, nil);

Now you have to enable and disable the various menu items. You could call MCGetControllerInfo, which returns a long word of flags indicating, among other things, which Edit menu items should be enabled.With QuickTime 1.5, there's an easier way: call MCSetUpEditMenu, and the movie controller will enable and disable the items in the Edit menu for you.

MCSetUpEditMenu(mc, theEvent.modifiers, editMenuHandle);
[IMAGE 022-025_Somewhere_in_QT_3.GIF]

Standard [IMAGE 022-025_Somewhere_in_QT_4.GIF]

Modified


This routine will even change the menu contents if appropriate. For example, Undo becomes Undo Paste if the last movie controller action was Paste; after Undo Paste is chosen, it becomes Redo Paste. What's more, if the user holds down modifier keys when pulling down a menu, other commands change as well. For example, holding down the Option key changes Paste to Add and Clear to Trim. (See Figure 2.)

Figure 2. Standard and modified Edit menus

MCSetUpEditMenu assumes the Edit menu is arranged in the standard way. If yours is nonstandard, you'll need to use MCGetMenuString to obtain the appropriate text for each standard Edit command, and then enable and disable the menu items according to the information from MCGetControllerInfo.

JUST DO IT
It's so easy to add movie playback support that it's often well worth the effort. As long as you keep these few simple things in mind, you shouldn't have any problems, even with future versions of QuickTime.

PETER HODDIE writes code to introduce hard-to-find bugs into QuickTime. In his spare time he writes code to introduce even harder-to-find bugs into QuickTime. *

Thanks to Jim Batson, Ken Doyle, and John Wang for reviewing this column. *

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

Things 3.1.3 - Elegant personal task man...
Things is a task management solution that helps to organize your tasks in an elegant and intuitive way. Things combines powerful features with simplicity through the use of tags and its intelligent... Read more
BetterTouchTool 2.292 - Customize Multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Things 3.1.3 - Elegant personal task man...
Things is a task management solution that helps to organize your tasks in an elegant and intuitive way. Things combines powerful features with simplicity through the use of tags and its intelligent... Read more
BetterTouchTool 2.292 - Customize Multi-...
BetterTouchTool adds many new, fully customizable gestures to the Magic Mouse, Multi-Touch MacBook trackpad, and Magic Trackpad. These gestures are customizable: Magic Mouse: Pinch in / out (zoom... Read more
Bookends 12.8.3 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
Mellel 3.5.5 - The word processor for sc...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
Mellel 3.5.5 - The word processor for sc...
Mellel is the leading word processor for OS X and has been widely considered the industry standard since its inception. Mellel focuses on writers and scholars for technical writing and multilingual... Read more
Bookends 12.8.3 - Reference management a...
Bookends is a full-featured bibliography/reference and information-management system for students and professionals. Bookends uses the cloud to sync reference libraries on all the Macs you use.... Read more
Carbon Copy Cloner 4.1.18 - Easy-to-use...
Carbon Copy Cloner backups are better than ordinary backups. Suppose the unthinkable happens while you're under deadline to finish a project: your Mac is unresponsive and all you hear is an ominous,... Read more
Hopper Disassembler 4.2.14- - Binary dis...
Hopper Disassembler is a binary disassembler, decompiler, and debugger for 32- and 64-bit executables. It will let you disassemble any binary you want, and provide you all the information about its... Read more

Little Red Lie (Games)
Little Red Lie 1.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0 (iTunes) Description: ARE YOU MORE AFRAID OF POVERTY THAN DEATH? Little Red Lie is a narrative-focused, interactive fiction experience that reduces... | Read more »
You can now apply to be Clash of Clans...
Earlier this month, word got out that the Builder, the trusty handiman who tirelessly built every single building inevery singleClash of Clansbase had called it quits. Sick of seeing his work destroyed endless, the Builder has set out for our world... | Read more »
Meshi Quest beginner's guide - how...
Meshi Quest is Square Enix's newest free-to-play release, and it's a real charmer. You start off as the head of a sushi restaurant, upgrading your food and equipment as you serve visitors heaping helpings of your delicious meals. As you progress,... | Read more »
BUST-A-MOVE JOURNEY (Games)
BUST-A-MOVE JOURNEY 1.0.0 Device: iOS Universal Category: Games Price: $4.99, Version: 1.0.0 (iTunes) Description: BUST-A-MOVE Features:- Shoot bubbles and match 3 or more bubbles of the same color to make them pop!- Complete your... | Read more »
The best card combos in Clash Royale
Clash Royale is all about building a deck of units that synergise well. To help you get off to a flying start, we've put together a list of unit combinations that are incredibly effective. Looking for some choice 2v2 combos? Check out our guide. [... | Read more »
The best 2v2 card combos in Clash Royale
2v2 is making it's grand return toClash Royalequite soon. 2v2 has quickly become one of the game's most popular gameplay modes, though they still have yet to make it a permanent fixture in the game. 2v2 is exciting and adds some new flavor to... | Read more »
The best games we played this week - Aug...
Another busy week has come to a close. We played a lot of excellent games this week and now it's time to look back and reflect on some our favorites. Here are our picks for the week of August 18. [Read more] | Read more »
War Wings beginner's guide - how to...
War Wings is the newest project from well-established game maker Miniclip. It's a World War II aerial dogfighting game with loads of different airplane models to unlock and battle. The game offers plenty of single player and multiplayer action. We... | Read more »
How to win every 2v2 battle in Clash Roy...
2v2 is coming back to Clash Royale in a big way. Although it's only been available for temporary periods of time, 2v2 has seen a hugely positive fan response, with players clamoring for more team-based gameplay. Soon we'll get yet another taste of... | Read more »
Roll to Win with Game of Dice’s new upda...
Joycity’s hit Game of Dice gets a big new update this week, introducing new maps, mechanics, and even costumes. The update sets players loose on an exciting new map, The Cursed Tower, that allows folks to use special Runes mid-match. If you feel... | Read more »

Price Scanner via MacPrices.net

Free Instant Translator 2.0 App For iOS Relea...
Mobile application development company, Neoappz has announced the release and immediate availability of Instant Translator 2.0 for iOS devices. Instant Translator is a user-friendly application which... Read more
2017 15-inch MacBook Pros on sale for $200 of...
Amazon has 2017 15″ MacBook Pros on sale for $200 off MSRP. Shipping is free: – 15″ 2.8GHz MacBook Pro Space Gray: $2199.99, $200 off MSRP – 15″ 2.8GHz MacBook Pro Silver: $2296, $103 off MSRP – 15″... Read more
Apple’s 2017 Back to School Promotion: Free B...
Purchase a new Mac using Apple’s Education discount, and take up to $300 off MSRP. All teachers, students, and staff of any educational institution qualify for the discount. Shipping is free. As part... Read more
Clearance 2016 12-inch Retina MacBooks, Apple...
Apple has Certified Refurbished 2016 12″ Retina MacBooks available starting at $1019. Apple will include a standard one-year warranty with each MacBook, and shipping is free. The following... Read more
15-inch 2.2GHz Retina MacBook Pro, Apple refu...
Apple has Certified Refurbished 2015 15″ 2.2GHz Retina MacBook Pros available for $1699. That’s $300 off MSRP, and it’s the lowest price available for a 15″ MacBook Pro. An Apple one-year warranty is... Read more
Apple refurbished Mac minis available startin...
Apple has Certified Refurbished Mac minis available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: – 1.4GHz Mac mini: $419 $80 off MSRP – 2.6GHz Mac... Read more
Apple refurbished iPad Pros available startin...
Apple has Certified Refurbished 2016 12″ WiFi iPad Pros available starting at $589. An Apple one-year warranty is included with each model, and shipping is free: – 32GB 12″ iPad Pro WiFi: $589... Read more
Weekend sale: 13-inch MacBook Pros for up to...
Amazon has new 2017 13″ MacBook Pros on sale today for up to $200 off MSRP, each including free shipping: – 13″ 3.1GHz/256GB Space Gray MacBook Pro (MPXV2LL/A): $1599.99 $200 off MSRP – 13″ 3.1GHz/... Read more
Back To School With The Edge Desk All-in-one...
Back to school is just around the corner, and the ergonomically correct Edge Desk all-in-one portable kneeling desk is ideal for students living in dorms and small apartments, Edge Desk features:... Read more
Norton Core Secure Wi-Fi Router Now Available...
First introduced at the 2017 Consumer Electronics Show (CES), Norton Core, a secure, high-performance Wi-Fi router, fundamentally changed the concept of Wi-Fi routers by making security the primary... Read more

Jobs Board

*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
Development Operations and Site Reliability E...
Development Operations and Site Reliability Engineer, Apple Payment Gateway Job Number: 57572631 Santa Clara Valley, California, United States Posted: Jul. 27, 2017 Read more
Frameworks Engineering Manager, *Apple* Wat...
Frameworks Engineering Manager, Apple Watch Job Number: 41632321 Santa Clara Valley, California, United States Posted: Jun. 15, 2017 Weekly Hours: 40.00 Job Summary Read more
*Apple* Solutions Consultant - Apple Inc. (U...
…about helping others on a team while also delighting customers? As an Apple Solutions Consultant (ASC), you will discover customers needs and help connect them Read more
*Apple* Solutions Consultant - Apple Inc. (U...
Job Summary As an Apple Solutions Consultant, you'll be the link between our future customers and our products. You'll showcase your entrepreneurial spirit as you Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.